Effectiveness Trial of a Dissonance-Based Obesity Prevention Program (Project Health)

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Obesity is a major US public health problem. Few obesity prevention programs have reduced risk for weight gain over follow-up and those that have are very intensive, making dissemination difficult and costly. A brief 3-hr selective prevention program (Healthy Weight) targeting young adults with body dissatisfaction involving participant-driven healthy dietary and physical activity lifestyle changes significantly reduced increases in body mass index (BMI) and obesity onset relative to alternative interventions and assessment-only controls through 3-yr follow-up, though effects were small in magnitude. To enhance efficacy, the investigators added dissonance-inducing activities regarding unhealthy dietary and activity practices, drawing from a highly efficacious dissonance-based eating disorder prevention program. A pilot trial found that this new Project Health intervention significantly reduced increases in BMI relative to both the Healthy Weight intervention and an educational brochure condition from pre to post. The investigators propose to conduct a rigorous multisite effectiveness trial that will test whether adding the dissonance-induction elements to the originally Healthy Weight intervention improves weight gain prevention effects. 360 college students at risk for future weight by virtue of their age and weight concerns will be randomized one of three conditions: (1) a refined 6-hr group-based dissonance-based Project Health, (2) a 6-hr group-based Healthy Weight intervention, or (3) a psychoeducational video ("Weight of the World") condition. Participants will complete assessments of % body fat, mediators (including objectively measured physical activity), moderators, and other outcomes at pre, post, and 6, 12, and 24 month follow-ups.

Aim 1 will test the hypothesis that Project Health significantly reduces increases in % body fat relative to the Healthy Weight intervention and video control condition during a 2-yr follow-up; secondary outcomes are BMI, depressive symptoms and eating disorder symptoms. The investigators will also compare Healthy Weight to video controls.

Aim 3 will test the hypothesis that intervention effects are amplified for participants with elevated body dissatisfaction (which should increase motivation change) and preference for consistency (which should maximize dissonance induction) and mitigated for participants who report emotional eating and substance use (because these factors increase risk for overeating).

The main goal of the Healthy Weight intervention is to make small, sustainable changes to input and output on a weekly basis to achieve a balance between caloric intake and output. All sessions begin with a brief review of what was covered in the previous session, presentation of educational handouts, careful review of previous behavior change goals, and the development of healthy behavior change plans for the next session. Home exercises for all sessions consist of following individualized diet and exercise goals, and keeping a food and exercise log to determine areas for future healthy changes.

Behavioral: Healthy Weight

Experimental: Project Health

Project Health adds dissonance-inducing activities, discussions, and homework activities to the Healthy Weight basic intervention. Each session begins with a verbal commitment to participate (to underscore the voluntary nature of participation), includes discussions of completed home practice assignments and in-session writing/sharing exercises (to create accountability), and concludes with home exercises (to increase level of effort). Completed home assignments are videotaped in subsequent sessions to increase accountability.

Behavioral: Project Health

Placebo Comparator: Control

Some participants will be randomized to control condition whereby they will be given an psychoeducational video ("Weight of the World")to view.

The Eating Disorder Diagnostic Interview, a brief semi-structured interview, will assess eating disorder symptoms. It provides diagnoses for anorexia nervosa, bulimia nervosa, and binge eating disorder, which will allow us to exclude participants with these disorders. It also provides a continuous measure of overall eating disorder symptoms.

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